The role indigenous livestock can play in Africa's Livestock Revolution is not always recognized. In many parts of Africa pure breeding with indigenous breeds is the only viable production strategy because of adverse climatic and nutritional conditions. However, there are scenarios where the higher demands of exotic breeds and their cross-breds can be met. This article discusses the possibility of improving beef production through terminal cross-breeding with two South African cattle breeds, the Nguni and the Afrikaner, with different exotic breeds. Calving difficulties were limited and birth weights were restricted to the mid-parent value or below. Cross-breeding did not have a negative effect on cow performance such as weight change and fertility, but cow productivity increased. In most cases the weaning weight of cross-bred calves was the same or exceeded that of the pure sire breed, and the feed conversion ratio was always better than either of the two parent breeds. This made the feedlot performance of the cross-breds highly desirable. These results indicate that terminal cross-breeding with indigenous African breeds deserves more attention as a means of increasing the output of beef cattle in the subtropics and tropics. An added advantage of any system of terminal cross-breeding utilizing indigenous breeds is that the conservation and utilization of the indigenous breeds of Africa is ensured, because a constant stream of purebred females will be required. resultados demuestran que cruces terminales con razas locales africanas merecen más atención como medio para incrementar la producción de carne de ternera en el subtrópico y trópico. Una ventaja añadida de cualquier sistema de cruces terminales es la utilización de razas locales, lo que asegura la conservación y la utilización de las razas locales de África, dado que se requerirán constantemente hembras criadas en pureza.Palabras clave: bovino local, cruce terminal, Nguni, Afrikaner, producción de ternera mejorada

Developing countries from the southern hemisphere will be confronted by the same beef production challenges caused by global warming, because these countries are at the same geographical positions in southern latitudes. Global warming is expected to have a more extreme effect on the southern hemisphere than on other continents and will have a negative effect on the beef production environments in these countries. The negative effects will include high ambient temperatures, nutritional stress and altered patterns of animal diseases. Heat stress in beef cattle on veld/savannah is expected to increase as a result of changing weather patterns on a global and regional scale. This may negatively influence food production from beef cattle for the human food chain. Negative effects of increased temperatures and thus heat stress can include lower reproductive rates and weaning weights. The effect of heat stress can be partly addressed by nutritional strategies, such as replacing rapid fermentable carbohydrates with saturated fatty acids and the feeding of more by-pass protein and dietary electrolytes. Global warming will also alter the distribution pattern of animal diseases and the vectors of some of these diseases. This may even include the spread to South American countries. Likewise the nutritional value of natural pastures may be influenced. The effect of global warming on the quality of pastures will depend on whether the global warming is a result of increased carbon dioxide levels or not. An improved understanding of the adaptation of beef cattle to their production environments is important, but adaptation is complex and thus difficult to measure. Fortunately, several proxy-indicators for adaptation such as reproductive, production and health traits are available. The selection of animals and genotypes that are better adapted to the production system, including heat stress, is possible and should be persuade to ensure sustainable beef production in hotter climates.

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Global warming is predicted to have a profound effect on livestock production in developing countries. An improved understanding of the adaptation of livestock to such changing production environments is thus important, but the measurement of adaptation is complex and difficult. Proxy-indicators for adaptation, such as reproductive and production traits, however, can be used. Livestock industries have a responsibility to reduce the release of greenhouse gases (i.e. the carbon footprint) and water use (i.e. the water footprint). An effective way of decreasing the carbon and water footprints from livestock is to reduce livestock numbers and increase the production per animal. Increased production generates less greenhouse gas emissions per unit of livestock product. Proper definition of breeding objectives and trait definition is essential in implementing efficient breeding systems to cope with climate change. Sophisticated statistical models continue to support animal breeding and improvement, especially with respect to production traits. Traits linked to fertility and survival are still problematic and appropriate genetic technology to properly characterize these traits needs to be developed. Gene or marker-assisted selection may play an important role in selection for disease and parasite resistance or tolerance, since it is generally difficult to measure these traits directly. Strategies that utilize breeding values derived from genomic analyses may speed up the process of breeding animals with higher and more efficient production and that are adapted to the changing environments as a result of global warming. However, both genetic and epigenetic controls influence genetic expression and should be taken into account when formulating breeding programmes. Subsistence farmers keep livestock for multiple purposes and the formulation of breeding objectives/strategies will have to consider these dynamics. ________________________________________________________________________________

________________________________________________________________________________ AbstractUsing breed differences effectively facilitates high productivity and profitability. Thus, the objective of the study was to estimate direct and maternal additive and heterosis effects for growth traits (birth weight, weaning weight, 19-month weight of heifers and cow weight) from five purebred and 24 crossbred breed types. Afrikaner (A), Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) were evaluated as purebreds and as sire breeds on A and F 1 BA, CA, HA and SA females. Breed additive effects were expressed as deviations from A. Effects of intra-breed genetic trend were assumed to be zero throughout. Solutions for the breed additive and heterosis effects were used to predict performance of the crossbred breed types to verify the adequacy of the genetic model. Correlations of observed and predicted means ranged from 0.87 for weaning weight to 0.94 for 19-month weight. Breed direct effects were consistently greatest for C and least for A across all traits, and maternal effects were greatest for S (except for 19-month weight) and least for C. Direct and maternal heterosis, on average, were positive for all weights. The indicus x sanga and indicus x taurus direct heterosis effects on all weight traits were greater than either the taurus x sanga or taurus x taurus effects, whereas the indicus x sanga maternal heterosis effect was consistently less than the estimated taurus x sanga maternal heterosis effect. ________________________________________________________________________________

Fitness is of paramount importance to efficient and profitable beef production. Thus, the objective of this study was to estimate genetic components of fitness traits measured in Afrikaner (A), Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S). For this study, the fitness traits recorded were percentage of cows exposed that were subsequently certified pregnant (PR), percentage of certified pregnant cows that subsequently calved (CR), percentage of calves born that survived to weaning (SV) and the percentage of cows exposed that ultimately weaned a calf (WR). Data were mean performance of straightbred, F1 cross, backcross and three-breed cross females. All crossbred females were of at least 25% A heritage. Breed group means were equated with their genetic expectations assuming recombination effects were nil and the heterosis effects were proportional to the expected heterozygosity in the crosses relative to the purebreds. With the exception of B-sired females from CA cross dams, the genetic model fit the breed group means with a high degree of fidelity. Breed-specific genetic effects tended not to individually exceed the magnitude of their standard errors. However, when the breed-specific genetic effects were combined to predict breed group means, the fitness of crossbred females, on average, exceeded that of their straightbred contemporaries. No particular advantage was noted for adding Brahman to the breed composition of crossbred females with at least 25% Afrikaner heritage. In summary, these data are viewed as being supportive of the use of breed resources in organized crossbreeding systems, such as two-and three-breed rotations that maintain at least 25% Afrikaner germplasm in the breeding females.

Livestock production impacts food security of developing countries, especially where efficiency of production is compromised by environmental stressors. In South Africa, breeding with indigenous Afrikaner cattle that are genetically well adapted to subtropical environments is considered an essential strategy for sustainable beef production. Today, there is a potential for farmers to participate in commercial systems that join adapted Afrikaner germplasm, used in a specialized maternal role, with exotic terminal sires to optimize production. The objective of this study was to assess productivity of five simulated production systems: 1) straightbred Afrikaner mated naturally, 2) a straightbred Afrikaner cow herd with two sections; one section to produce replacement females and the other to cross with Charolais terminal sires, both using natural mating, 3) similar to 2, but applying sexed semen to produce replacement females, 4) similar to 2, but using a multi-breed composite dam line with a breed combination of 50% Afrikaner, 25% Hereford and 25% Simmental, and 5) similar to 4, but again applying sexed semen to produce replacement females. Parameter estimates needed to compare these systems were extracted from the scientific literature. Relative to straightbred Afrikaner dams, the simulated composite dams were more fit producing 7.8% more calves and their progeny performance was improved by reducing feed intake (−24.4%) and increasing meat production (+11.7%). The potential benefit of allocating more cows to the terminal sire was insufficient to offset the reduction in pregnancy rate that results with the use of sexed semen. Thus, system 4 had How to cite this paper: Khorshidi, R.,

Context It is desirable to identify cows that produce higher weaning weights while consuming less feed in order to increase biological efficiency; however, there is no universally accepted metric for cow–calf efficiency. Aim Due to the common usage of ratios to express biological cow efficiency, despite their theoretical defects, these measures and alternatives to them were examined to understand better some of the complexities in improving cow efficiency. Methods The analyses were carried out using SAS. In model 1, 205-day calf weight/cow weight was used to define cow–calf efficiency and in model 3, 205-day calf weight per Large Stock Unit (LSU), which is a standard unit of energy consumed, was used to quantify efficiency. In models 2 and 4, 205-day calf weight was analysed using cow weight and Large Stock Unit, respectively, as covariates. Key results The use of ratios was biased in favour of the smaller Nguni cows. The Bonsmara and Angus sired calves attained 53% of the weight of their Nguni dams, and their weaning weight per Large Stock Unit was 169 ± 9 kg. However, Angus sired calves from Bonsmara dams were most efficient when efficiency was determined by analysis of covariance when cow weight and Large Stock Unit were used as covariates (162 ± 17 kg and 133 ± 22 kg), respectively. Conclusions The results indicate the difficulty in determining differences in cow–calf efficiency in the absence of a standard definition. The difference between output and input can be maximised, when traits are reported in consistent units like joules, financial currency, or carbon footprint. Implications This inconsistent definition of cow–calf efficiency makes its improvement challenging.